Origins
The word 'pepper' is one of the oldest spice-trade words in European languages, tracing a route from the Sanskrit-speaking world of ancient India through Greek and Roman intermediaries to the Germanic languages of northern Europe. English 'pepper' comes from Old English 'pipor,' borrowed from Latin 'piper,' from Greek 'péperi' (πέπερι), ultimately from an Indic source. The most commonly cited origin is Sanskrit 'pippalī' (पिप्पली), the name for long pepper (Piper longum), a spice native to the Indian subcontinent.
The identification of the Sanskrit source is significant because it reveals which species of pepper first reached the Mediterranean world. Long pepper (Piper longum) — a spike-shaped fruit quite different in appearance from the familiar round peppercorns — was the dominant pepper in ancient Greek and Roman cuisine. Theophrastus, writing in the fourth century BCE, distinguished between 'péperi' (long pepper) and a round variety, but the name attached primarily to the long form. It was long pepper that Hippocrates recommended as a medicine, mixed with honey and vinegar.
Black pepper (Piper nigrum), which grows on the same subcontinent but produces the small round berries familiar to modern kitchens, gradually overtook long pepper in European markets during the medieval period. The reasons are complex: black pepper was more abundant, easier to transport, and more consistent in flavor. But it inherited the name 'pepper' from its predecessor — meaning that the English word technically derives from the name of a different species than the one it now primarily denotes.
Germanic Development
The Latin form 'piper' entered the Germanic languages very early, during the period of contact between Germanic peoples and the Roman Empire (roughly the first through fifth centuries CE). The word's presence in all the major Germanic languages — Old English 'pipor,' Old High German 'pfeffar' (modern German 'Pfeffer,' with the characteristic High German consonant shift of p → pf), Old Norse 'piparr,' Dutch 'peper' — confirms that the borrowing occurred at the Proto-West-Germanic or even Proto-Germanic stage.
The Romance languages show their own regular developments: French 'poivre' (from Vulgar Latin *pipere, with the characteristic French vocalization of intervocalic 'p' and other changes), Italian 'pepe,' Spanish 'pimienta' (for the spice) and 'pimiento' (for the capsicum pepper plant), Portuguese 'pimenta.' The Spanish and Portuguese forms are particularly interesting because they applied the old word 'pepper' to the capsicum plants (chili peppers, bell peppers) encountered in the Americas — plants that are completely unrelated to true pepper (Piper) but share the quality of pungency.
This terminological confusion persists in English: 'pepper' refers both to the berries of Piper nigrum (black, white, and green peppercorns) and to the fruits of Capsicum (bell peppers, chili peppers, cayenne). The two plant families are not even in the same order of classification. The confusion arose because Columbus, seeking a westward route to the pepper-producing East Indies, encountered pungent Capsicum fruits in the Caribbean and called them 'peppers' in an optimistic (and botanically incorrect) identification.
Latin Roots
Pepper was one of the most valuable commodities in the ancient and medieval world. The Roman author Pliny complained about the drain of gold from Rome to India to pay for pepper. In medieval Europe, peppercorns were so valuable that they were used as currency — the term 'peppercorn rent' (a nominal rent) preserves this usage, though its modern meaning (trivially small) inverts the medieval reality, in which a peppercorn was anything but trivial. The Dutch word 'peperduur' (pepper-expensive, meaning very expensive) similarly preserves the historical value of the spice.